Thin Film Transistor-Liquid Crystal Displays (TFT-LCDs) have been widely used in various electronic apparatuses with display function, such as Televisions (TVs), monitors, portable electronic devices, etc. Presently, manufacturers are making efforts to enhance properties of the TFT-LCDs so as to reduce power consumption, enlarge viewing angle and decrease response time. Among various efforts of enhancing properties of the TFT-LCDs, improvement to image sticking is essential because it directly affects the display quality.
The image sticking refers to a phenomenon that, when a certain still image is changed to other image after it has been displayed for a long time, profile of the image retains. Depending on forms and locations, the image sticking is classified into two types: an area image sticking and a line image sticking. Study on mechanism of the image sticking shows that the image sticking is mainly resulted from residual charges, and the residual charges comprise polarized charges that are generated inside a liquid crystal display panel under an external electric field and impurity charges inside the liquid crystal display panel. These residual charges affect orientations of liquid crystal molecules at the top and bottom portions of the liquid crystal display panel and results in the image sticking. Occurrence of the image sticking can severely affect the display effect of the liquid crystal display. Further, in a peripheral region of the liquid crystal display panel, liquid crystal molecules may contact with a sealant and be polluted, thus impurity ions may be easily generated, and the line image sticking may occur after the impurity ions gather to a certain degree. Therefore, the line image sticking mostly occurs in the peripheral region of the liquid crystal display.